000
NOAK48 PAFC 132015 CCA
PNSAFC
AKZ155-202000-

PUBLIC INFORMATION STATEMENT...CORRECTED
NATIONAL WEATHER SERVICE ANCHORAGE AK
1115 AM AKST MON JAN 13 2020

...DATUM/BASELINE VALUE REPORTED BY THE NATIONAL WEATHER SERVICE
TO CHANGE AT TUNUNAK ALONG THE COAST OF THE KUSKOKWIM DELTA...

ON FEBRUARY 12 2020 THE NATIONAL WEATHER SERVICE (NWS) FORECAST
OFFICE IN ANCHORAGE ALASKA AND THE ALASKA-PACIFIC RIVER FORECAST
CENTER (APRFC) WILL BE CHANGING THE DATUM (BASELINE) FOR THE 
TIDAL GAGE AT TUNUNAK ALONG THE COAST OF THE KUSKOKWIM DELTA 
(SITE TNUA2).

THE WATER LEVEL REPORTED BY THE NWS WILL NOW READ 6.35 FEET 
LOWER THAN PREVIOUSLY REPORTED. THIS DATUM CHANGE IS BEING MADE
AS A RESULT OF A RECENT GPS SURVEY AND ESTABLISHMENT OF A MORE
ACCURATE MEAN LOWER LOW WATER (MLLW) DATUM AT THIS GAGE LOCATION.
NEW DATA DISPLAYED AT THE TUNUNAK GAGE WILL BE REFERENCED TO THE
MLLW TIDAL DATUM. FOR MORE INFORMATION ON COASTAL DATUMS SEE 
THIS LINK: HTTPS://TIDESANDCURRENTS.NOAA.GOV/DATUM_OPTIONS.HTML.

EXAMPLE OF THE SUMMARY OF CHANGES TO THE BASELINE DATUM FOR MLLW:

OLD VALUE       NEW VALUE       CHANGE

21.91 FT.       15.56 FT.       -6.35 FT.

COMMENTS AND QUESTIONS ABOUT THIS CHANGE SHOULD BE DIRECTED TO:

JOE WEGMAN
ACTING SENIOR SERVICE HYDROLOGIST 
NWS ANCHORAGE 
JOSEPH.WEGMAN AT NOAA.GOV

$$

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